Slotted plate type electrical connections

ABSTRACT

Connecting device for forming an electrical connection with a wire or the like comprises a strip of conductive metal which is folded intermediate its ends to form a V-shaped center portion having a bight and sides. The sides are bent outwardly to define end portions extending in opposite directions. A wire receiving slot extends from the one end portion through the sides and bight of the V-shaped section and into the other end portion.

[ July 22, 1975 United States Patent Wasserlein, Jr.

[ 4] SLOTTED PLATE TYPE ELECTRICAL CONNECTIONS [75] Inventor: HenryGeorge Wasserlein, Jr.,

Seminole, Fla.

Primary Examiner-Joseph H. McGlynn 0r Firm-F. W. Raring; Jay Seitchik;

t n e g A v e n r 0 t t A a P am r u b S n r a H d e t m 04 mm 01 m, M mA] a e n: .w d SC AF MM 72 W. J. Keating [2]] Appl. No.: 436,292

ABSTRACT Connecting device for forming an electrical connection with awire or the like comprises a strip of con- Related US. Application DataContinuation of Ser. No; 257,897, May 30, 1972, abandoned.

ductive metal which is folded intermediate its ends to form a V-shapedcenter portion having a bight and sides. The sides are bent outwardly todefine end portions extending in opposite directions. A wire receiv- 899 wk 05 .HN ".9 "3 WW mmhn n. r. "3 6 e mu II. C WM UmF M M 555 [56]References Cited ing slot extends from the one end portion through theUNITED STATES PATENTS sides and bight of the V-shaped section and intothe other end portion.

3,168,615 2/1965 Owen et 339/98 3,235,833 2/1966 Elm 339/97 P 5 Clams,17 Drawlng Flgures SHEET PATENTED L 2 2 SLOTTED PLATE TYPE ELECTRICALCONNECTIONS This is a continuation of application Ser. No. 257,897,filed May 30, 1972, now abandoned.

BACKGROUND OF THE INVENTION A widely used type of connecting devicecomprises a plate-like member of conductive metal having a wirereceiving slot extending inwardly from one of its edges. The width ofthe slot is somewhat less than the diameter of the wire which is adaptedto be connected to the device so that when the wire is moved laterallyof its axis into the slot, the tines on each side of the slot are wedgedoutwardly in their own planes in the manner of cantilever beams. Theresilient deflection of these tines provides continuing forces at theinterfaces of the wire and the edges of the slot which gives rise to ahigh quality, low resistance electrical connection. Electricalconnecting devices of this general type are disclosed in US. Pat. Nos.2,501,187; 3,012,219; 3,617,983; and in numerous other issued patentswhich disclose specific embodiments adapted for specializedapplications. It is unnecessary to strip insulation from the wire priorto insertion and for this reason, and for the additional reason that anexcellent electrical connection is obtained, these wire-in-slotconnecting devices are being enthusiastically received in the electricalindustry.

As explained above, the simpliest form of wire-in-slot connectingdevices comprises a simple plate-like member having a slot extendinginwardly from one of its edges. U.S. Pat. No. 3,617,983 shows animproved device in which the plate-like member is folded intermediateits ends and the slot extends intothe bight of the folded member andpartially into the two plate sections formed as a result of the fold.These known devices depend upon a relatively stiff spring system, thecantilever beams on each side of the wire receiving slot havingrelatively high spring rates and being capable of undergoing onlylimited elastic deflection during insertion of the wire. Because ofthese factors, the force required to insert the wire into the slot ofthe connecting device is relatively high and in addition, these devicesmust be manufactured under close and exacting dimensional tolerances ifconsistantly high electrical performance devices are to be produced.Additionally, the engineer designing a wire-in-slot connecting typedevice in accordance with present engineering practice and accepteddesign criteria has only a limited choice as regards dimensions,material, and expected insertion force for the wire.

The present invention is directed to the achievement of an improvedwire-in-slot type connecting device which will overcome manufacturingand application (i.e. insertion force) shortcomings of the presentdesign. To these ends, the invention is directed to the achievement of awire-in-slot type connecting device having a .low rate and controllablespring system and having design features such that only a low insertionforce is required to push the wire into the slot of the connectingdevice.

It is accordingly an object of the invention to provide an improvedwire-in-slot type connecting device. A further object is to provide animproved wire-slot connecting device having improved spring systems formaintaining contact pressure between the wire and the edges of the slot.A still further object is to provide a wire-slot connecting device whichutilizes torsional deflection of the crmnecting device as a means forestablishing contact force with the wire. A still further object is toprovide a wire-in-slot connecting device which need not necessarily bemanufactured to extremely close or critical dimensional tolerances. Afurther object is to provide a wire in slot connecting device having aspring rate for establishing electrical contact which is substantiallyconstant over a relatively wide range of deflection. A further object isto provide improved insulating housings for wire-in-slot type connectingdevices.

These and other objects of the invention are achieved in preferredembodiments thereof which are briefly described in the foregoingabstract, which are described in detail below, and which are shown inthe accompanying drawing in which:

FIG. 1 is a perspective view of a metallic wire-in-slot type connectingdevice in accordance with the invention, this view illustrating theappearance of the device prior to insertion of the wire.

FIG. 2 is a view similar to FIG. 1 but showing the appearance of thedevice after insertion of the wire, the resilient deflection of thedevice being exaggerated in this view for purposes of illustration.

FIG. 2A is a view taken along the lines 22 of FIG. 2.

FIGS. 3 and 4 are fragmentary diagramatic views illustrating the mannerin which the edges of the slot in the connecting device establishelectrical contact with the wire during insertion of the wire into theslot.

FIG. 5 is a diagramatic side view of the connecting device illustratingtwo modes of stressing the connecting device.

FIG. 6 is a diagramatic view of the area of contact of the wire in theconnecting device and illustrating the fact that the contact area isenlarged in accordance with the invention.

FIG. 7 is a perspective view of an alternative embodiment of a metallicconnecting device in accordance with the invention.

FIG. 8 is a perspective exploded view of a connector comprising ametallic connecting device and housing in accordance with the invention,the cap member of the housing and the metallic connecting device beingexploded from the base member of the housing in this view.

FIG. 9 is a sectional side view of the wire connector of FIG. 8 showingthe parts assembled to each other and showing the location of a wireinserting into the connecting device.

FIG. 10 is a perspective exploded view of an alternative form of aconnector which is adapted to connect the end of one wire to anintermediate portion of another wire. a

FIG. 11 is a sectional side view of the wire connector of FIG. 10.

FIG. 12 is a perspective view of a multi-contact connector forconnecting each one of a plurality of wires to individual conductors ona printed circuit board.

FIGS. 13-16 show alternative forms of connecting devices in accordancewith the invention.

Referring first to FIGS. 1 and 2, a metallic connecting device for asingle wire in accordance withthe gen eral principles of the inventioncomprises a metallic plate 2 which is folded intermediate its ends toform a V-shaped central portion having a bight 8 from which divergentsides 10 extend. The included angle between the sides is not critical,an angle of 60 being satisfactory formost' purposes. The sides 10 arebent outwardly at 12 to provide oppositely directed end sections 14. g Y

A wire-receiving slot 16 extends for substantially the full length ofthe connecting device and has a dead end in each of the end portions 14.This slot is of uniform width throughout most of its length but isenlarged as shown at in the vicinity of the bight 8 to facilitateinsertion of the wire into the slot. The portions of the slot .16 whichextend into the end sections 14 divide each of these end sections intotwo plate sections 22, which function as separate torsion spring membersin a manner described below.

Connecting devices in accordance with the invention can be manufacturedfrom a variety of materials such as a suitable brass, berillium copper,or phosphor bronze and can bedimensioned to accept a variety of wiresizes. Furthermore, a properly divisioned connecting device will accepta range of wire sizes.

When it is desired to connect the conducting core 4 of a wire 6 to theconnecting device, the wire is simply positioned in alignment with, andspaced from, the slot 16 and is then moved laterally of its axis throughthe enlarged slot portion 20 and into portions of the slot extendingalong the sides 10. In the finished connection, the wire extendsparallel to the end sections 14 and extends through the slot in each ofthe sides 10 as shown in phantom FIGS. 2 and 3.

During initial movement of the wire into the slot, the edges of the slotengage the surface of the wire as indicated diagramatically at 24 inFIG. 3. Upon further movement of the wire into the slot, these edges 24are forced into the insulation of the wire and the areas of contactbetween the wire and the edges move relatively along the wire axis sothat in the finished connection, FIG. 4, the conducting core of the wirewill be exposed adjacent to the sides 10 and will be in electricalcontact with the edges of the slot.

The connecting device 2 is elastically deformed and stressed in severalmodes by the wire and this elastic deformation of the connector providesspring forces at the interfaces of the wire and the edges of the slot tomaintain electrical contact between the parts. One mode of elasticdeformation is produced by virtue of the fact that the wire, relative tothe slot, moves the two sides of the V-shaped section in oppositedirections along a slightly arcuate path relative to the bends 12 at theends of the sides. This movement of the sides of the V-section producemoments in the sections 22 which can be considered to be centered at 13in FIG. 2, so that the sections 22 are torsionally flexed along theirlengths. This torsional effect is achieved by virtue of the fact thatthe outer ends of the sections 22 are fixed against rotative movement intheir own planes.

The torsional deflection described above provide four separate low-ratespring systems for maintaining the contact forces between the wire andthe edges of the slot and is achieved because of the fact that theseslots extend into the end sections 14.

The four separate torsional spring systems are established by virtue ofthe fact that each of the plate sections 22 in each of the end portions14 is independently torsionally stressed. This mode of resilientdeformation in the connector is to be compared with the stiffflexibility of the cantilever type loading which is relied upon inpreviously known wire-in-slot connecting devices.

The torsional spring systems described above are not only the onlyspring effects which are obtained in accordance with the invention.Referring to FIG. 5, the movement of the wire into the slot also has theeffect of introducing stresses which tend to bow the sides 10 (thisbowing being exaggerated in FIG. 5 for purposes of clarity). Thestresses tending to cause this bowing of the sides provide a componentof contact pressure for urging the edges of the slot against the wire.Additionally, the bight 8 may be resiliently deformed to a slight extentin the manner of an inwardly 'flexed hairpin to further contribute tothe maintenance of the contact pressure. Finally, the outward movementof the V- shaped sections and the sections 22, will give rise to somecantilever spring effect aside from the torsional stressing modedescribed above.

The precise contribution of the several modes of deflection to the totalcontact force developed cannot be determined and will, in any event,depend upon several factors which may vary, such as the size of the wirerelative to the width of the slot, the nature of the material from whichthe connector is made, and the thickness of the stock metal. Thetorsional effect is the most significant stressing mode and provides thelow rate spring system for maintenance of contact pressure.

From the standpoint of the engineer faced with the task of designing aparticular wire-in-slot connecting device intended for use under aspecific set of circumstances, the present invention offers theadvantage of permitting the achievement of any one of a wide variety ofend results. For example, if the connecting device must have arelatively high. contact force and must have a somewhat stiff springsystem (as may be required for a connecting device intended for use withsolid aluminum or stranded copper wires) the connector can bemanufactured from relatively hard material having a high elastic modulusand the end sections 14 can be shortened so that the torsional springsystem will be a relatively stiff spring system. On the other hand, ifit is desired to produce a connecting device which will undergo asubstantial amount of deflection when the wire is inserted and whichwill have a low spring-rate which is reasonably constant over a widerange of deflection, the end sections 14 can be lengthened. The width ofthe slot 16 relative to the length of the end sections and the physicalproperties of the stock metal provides a further means of controllingthe spring characteristics of the finished device. A device having arelatively low spring-rate and designed to undergo a substantial amountof deflection may be desirable when the connector is intended for usewith ordinary stranded copper wire.

Under some circumstances, it may be desirable to rely upon the contactbetween the wire and one of the plate sections 10 for electrical contactand to rely upon the other plate section 10 primarily as a means formechanically joining the wire to the connecting device, in other words,to provide a strain relief on the wire in order to safeguard theelectrical connection between the wire and the connecting device. Aconnecting device having such a strain relief connection in combinationwith an electrical connection can be provided by making one of the endsections 14 relatively short so that a stiff spring system will beestablished between the side 10 which is adjacent to this short endsection 14 and the wire. The other end section can be made relativelylong to provide a low-rate spring system for the mechanical connectionto the wire and the strain relief effect.

The V-shape form in the connecting device of FIGS. 1 and 2 offersadvantages in addition to the spring system advantages described abovein that an improved stripping effect is achieved. Referring to FIGS. 3and 4, the edges of the slot 16 contact the wire as shown at 24immediately after the wire passes through the enlarged portion 20 of theslot in the bight 8. As the wire moves relatively further into the slot,these zones of Contact 24 move relatively axially along the wire andaway from each other as shown in FIG. 4. In other words, the edges ofthe slot 16 move axially along the wire as insertion proceeds and the.insulation is skived or scraped from the surface of the wire. Thismethod of penetrating the insulation is to be compared with the methodrelied upon in known wire-in -slot type connecting devices of extrudingthe insulation from the area of contact as the wire is forced into theslot.

It should also be noted that an increase in the. contact area of thewire and slot edge interfaces is achieved by virtue of the fact that theedges of the slot extend obliquely, rather than normally, with respectto the axis of the wire. The actual extent to which contact area isincreased will depend upon the included angle between the sides 10, thegreater the angle, the greater the increase in contact area. An includedangle of 60 will provide an increase of about 15% in the contact areawhich can be distinctly advantageous when it is desired to maintain aminimum stock thickness in the connecting device.

By virtue of the fact that the slot 16 extends into the end sections 14,it is impossible to force the wire against the dead ends of the slotduring inserting so that it is therefore virtually impossible to damagethe wire or to sever it by the application of an unduly high insertionforce. This feature of the invention thus minimizes the possibility ofsevering of the wire or some of the strands thereof, a type of damagewhich may not be apparent immediately after insertion but which wouldresult in inferior performances during use and/or failure after therepeated temperature cycling which takes place during the life of anelectrical contact.

Under some circumstances, it may be desirable to form connecting devicesin accordance with the invention as shown in FIG. 7 with the sides 10aextending parallel to, and against each other. This embodiment providesa shorter connecting device, other things being equal, than thepreviously described embodiments and achieves the improved springeffects discussed above although it does not provide the improvement incontact area or insulation stripping of the previously describedembodiments.

FIGS. 13-15 show alternative forms of metallic connecting devices inaccordance with the invention, all of which are torsionally deformedupon insertion of a wire in accordance with the principles discussedabove. The embodiment 90 of FIGS. 13 and 14 is triangular as are theprevious embodiments and has end plate sections 94 which are bentinwardly so that they abut at 96. The slots extend partially into theseend sections so that the torsional effect is achieved.

FIG. 15 shows a simple L-shaped connecting device 100 having arms 100and 102. The slot extends fully through the arm 100 and partially intothe arm 102. FIG. 16 shows a channel-shaped connector 104 having a web106 and sides 108. The slots extend into and through the sides 108 andpartially into the web 106. The sides may be formed slightly inwardly asshown so that upon insertion of the wire or wires (if one wire isinserted into each slot) the legs may be flexed slightly outwardly toadd that mode of stressing to the torsional and cantilever modes.

Connecting devices in accordance with the invention can be manufacturedin a variety of forms for a variety of uses. For example, the connectingdevice of FIGS. 1 and 2 might be provided with a terminal portion in theform of a ring tongue or the like on either of the ends 14.Alternatively, connecting devices in accordance with the invention canbe provided with insulating housing as will now be described.

FIGS. 8 and 9 show a multi-wire connector 28 comprising a housing havinga base 30 and a cap or closure 32. The base has a cavity 40 therein, thefloor of which is recessed at 41 for the accomodation and the preciselocation of a metallic connecting device 34 which is in general inaccordance with the principles described above. This connecting devicehas a flange 36 extending from one of its end portions that serves tolocate it in the cavity 40 against a wall thereof. The connecting device34 comprises three separate wire-receiving slots which in turn areseparated from each other by separator slots 38. The separator slotsisolate the three individual connecting devices from each other so thatthey can behave individually upon the insertion of the wire inaccordance with the considerations discussed above.

Base 30 has a laterally extending arm 42 through which openings 44extend to the cavity'40. The cap 32 has depending flanges 46 on twoopposite sides thereof which are disposed against the sidewalls of thebase when the cap is positioned in the base, interengaging dimple andrecess means 50, 51 being provided to lock the cap in position.

The cap is additionally provided with two spaced apart legs 48 on itsunderside which function to push he the wires extending through theopening 44 into the slots in the connector device 34 and to retain thewires in the slots after insertion.

The housing of FIGS. 8 and 9, and the insulating housings describedbelow can be manufactured from any suitable thermo-plastic such as anylon which is relatively firm in thick sections which can be flexed inthin sections to permit the flexure of the legs 48 as shown in FIG. 9.

FIGS. 10 and 11 show a further embodiment which is adapted to form anelectrical connection between the end of one wire and an intermediateportion of another wire. The housing of this embodiment comprises a base54 having a cavity 58 from which insertion bars or legs extend. As withthe previously described embodiment, the wires are inserted into thecavity 48 through openings 62 in an arm 64 of the housing.

The cap member 56 has depending flanges 57 which fit within the cavity58 and the metallic connecting device 59 is mounted against the upperwall of this cap member between these flanges.

In use, the end portion of one wire is inserted through the opening 62and the connector is moved laterally with respect to the other wire sothat the other wire can move relatively through a passageway 66 untilthe through wire is located in the other one of the openings 62. The capmember is then simply pushed downwardly as viewed in the drawing and thewires are forced relatively into the slots.

FIG. 12 shows an embodiment 70 for forming disengageable electricalconnections between each of a plurality of wires and the conductingpaths 71 on a printed circuit board 76. This connector 70, comprises anelongated housing 72 having a trough 74 extending inwardly from itslefthand side for reception of the printed circuit board. Trough 74communicates with a cavity 78 which is divided into separatecompartments by barrier walls, each compartment having a connectingdevice 80 mounted therein. Again, the connecting devices 80 are inaccordance with the principles previously described and in addition,have a reversely bent contact arm 82 which extends from one of the endsections, the bight 83 of this arm being received within a recess 84 forpurposes of location and positioning. The opposite end section is simplysupported on the ledge 87.

The underside of the arm of each contact member is adapted to engage aconductor on the printed circuit board 76 as shown. The individual wiresare connected to the connecting device by inserting them throughopenings 90 until they are in alignment with the wire receiving slot ofthe connecting device. The cap piece or cover plate 86 is then assembledto the base section 72 of the housing, this cap piece having dependinglegs 88 for forcing the wires into the slots of the connecting devicesas previously described.

If desired, connecting devices of the type shown in FIG. 12 can beadapted to receive individual contact pins or posts rather than printedcircuit boards. In such a modification, separate openings for theindividual pins would be provided on the lefthand side of the connectorrather than a conductor through as in the disclosed embodiment.

What is claimed is: 1. An electrical and mechanical connection between aconductor and a terminal member,

said terminal member comprising a plate-like member of conductive sheetmetal, said member being bent transversely of its length at a locationspaced from one end thereof to define an end section and aconductor-receiving side section a wire-receiving slot extending intosaid conductorreceiving side section and extending for the full lengthof said side section and into said end section,

said slot having a dead end in said end section,

" said conductor being wedged in, and extending transversely through,said slot in said side section only, portions of said side section oneach side of said slot being flexed outwardly and away from each otherto provide a first spring system maintaining edge portions of said slotin engagement with said conductor, and

portions of said end section on each side of said slot being torsionallystressed in opposite rotary directions to provide a second spring systemmaintaining said edge portions of said slot in engagement with saidconductor.

2. An electrical and mechanical connection as set forth in claim 1, saidterminal member being substantially L-shaped.

3. An electrical and mechanical connection as set forth in claim 1, saidterminal member having a second conductor-receiving side section and asecond end section, said second side section being integral with saidside section, said conductor extending through said slot in said sidesection and through said slot in said second side section only.

4. An electrical and mechanical connection between a connecting deviceand an elongated conductor comprising:

a conductive slot metal member, said member being folded intermediateits ends and transversely of its length to the form of a V having abight and divergent sides, said sides being transversely of the lengthof said member to define oppositely directed end portions extending fromthe ends of said sides,

a conductor-receiving slot in said member extending along the lengththereof, said slot having dead ends in said end portions of said memberand said slot extending in both of said end portions and continuously insaid sides, said slot intersecting said bight,

said conductor having its axis extending parallel to said slot andextending through said slot in each of said sides only, said conductorbeing wedged between the opposed edges of said slot at contactlocations, portions of said member on each side of said slot beingresiliently flexed outwardly and away from each other in oppositedirections and portions of said end portions on each side of said slotbeing torsionally stressed in opposite rotary directions.

5. An electrical and mechanical connection between at least two wirescomprising:

a sheet metal plate-like member, said member being folded transverselyof its length at a location intermediate its ends to define a V-shapedsection having a bight and sidewalls which diverge from said bight, saidsidewalls being bent transversely of their lengths to define endportions which extend in opposite directions from said sidewalls,

two slots in said member, said slots extending from said bight throughsaid sidewalls and into said end portions, said slots having dead endsin each of said end portions, at least portions of said slots in saidsidewalls having a width which is less than the thickness of said wires,

said wires being in parallel side-by-side relationship with one wire ineach of said slots, said wires each having an end portion extendingthrough said slots in each of said sidewalls only, portions of saidsidewalls on each side of each slot being elastically flexed in oppositedirections by said wires, and portions of said end sections on each sideof each slot being torsionally flexed by stresses transmitted from saidoutwardly flexed portions of said sidewalls whereby said wires areresiliently held in said slots,

housing means enclosing said plate-like member and said end portions ofsaid wires, said housing means comprising a housing base and a housingclosure, said housing base having an open-sided cavity therein, saidplate-like member being disposed in said cavity, openings in saidhousing base communicating with said cavity, said end portions of saidwires extending through said openings, said closure member beingassembled to said base member and serving as a closure for said openside of said cavity,

said plate-like member being oriented in said cavity with said endportions of said plate-like member disposed against the side of saidcavity which is opposite to said open side and with said bight proximateto said open side, said housing closure having a pair of spaced-apartintegral legs extending therefrom, said legs being in straddlingrelationship to said bight and having their free ends against said wiresthereby to retain said wires in said slots.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Q PATENT NO.,:3,895,852

DATED July 22, 1975 INVENTOR(S) HENRY GEORGE WASSERLEIN, JR.

It is certified that error appears in the ab0ve-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 8, Claim 4, line 9, after"being" insert --bent-.

d r d h Engncd an Sea 6 t 15 sixteenth Day of September 1975 [SEAL]Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ommr'ssiuneruj'Parents and Trademarks

1. An electrical and mechanical connection between a conductor and aterminal member, said terminal member comprising a plate-like member ofconductive sheet metal, said member being bent transversely of itslength at a location spaced from one end thereof to define an endsection and a conductor-receiving side section a wire-receiving slotextending into said conductor-receiving side section and extending forthe full length of said side section and into said end section, saidslot having a dead end in said end section, said conductor being wedgedin, and extending transversely through, said slot in said side sectiononly, portions of said side section on each side of said slot beingflexed outwardly and away from each other to provide a first springsystem maintaining edge portions of said slot in engagement with saidconductor, and portions of said end section on each side of said slotbeing torsionally stressed in opposite rotary directions to provide asecond spring system maintaining said edge portions of said slot inengagement with said conductor.
 2. An electrical and mechanicalconnection as set forth in claim 1, said terminal member beingsubstantially L-shaped.
 3. An electrical and mechanical connection asset forth in claim 1, said terminal member having a secondconductor-receiving side section and a second end section, said secondside section being integral with said side section, said conductorextending through said slot in said side section and through said slotin said second side section only.
 4. An electrical and mechanicalconnection between a connecting device and an elongated conductorcomprising: a conductive slot metal member, said member being foldedintermediate its ends and transversely of its length to the form of a Vhaving a bight and divergent sides, said sides being transversely of thelength of said member to define oppositely directed end portionsextending from the ends of said sides, a conductor-receiving slot insaid member extending along the length thereof, said slot having deadends in said end portions of said member and said slot extending in bothof said end portions and continuously in said sides, said slotintersecting said bight, said conductor having its axis extendingparallel to said slot and extending through said slot in each of saidsides only, said conductor being wedged between the opposed edges ofsaid slot at contact locations, portions of said member on each side ofsaid slot being resiliently flexed outwardly and away from each other inopposite directions and portions of said end portions on each side ofsaid slot being torsionally stressed in opposite rotary directions. 5.An electrical and mechanical connection between at least two wirescomprising: a sheet metal plate-like member, said member being foldedtransversely of its length at a location intermediate its ends to definea V-shaped section having a bight and sidewalls which diverge from saidbight, said sidewalls being bent transversely of their lengths to defineend portions which extend in opposite directions from said sidewalls,two slots in said member, said slots extending from said bight throughsaid sidewalls and into said end portions, said slots having dead endsin each of said end portions, at least portions of said slots in saidsidewalls having a width which is less than the thickness of said wires,said wires being in parallel side-by-side relationship with one wire ineach of said slots, said wires each having an end portion extendingthrough said slots in each of said sidewalls only, portions of saidsidewalls on each side of each slot being elastically flexed in oppositedirections by said wires, and portions of said end sections on each sideof each slot being torsionally flexed by stresses transmitted from saidoutwardly flexed portions of said sidewalls whereby said wires areresiliently held in said slots, housing means enclosing said plate-likemember and said end portions of said wires, said housing meanscomprising a housing base and a housing closure, said housing basehaving an open-sided cavity therein, said plate-like member beingdisposed in said cavity, openings in said housing base communicatingwith said cavity, said end portions of said wires extending through saidopenings, said closure member being assembled to said base member andserving as a closure for said open side of said cavity, said plate-likemember being oriented in said cavity wIth said end portions of saidplate-like member disposed against the side of said cavity which isopposite to said open side and with said bight proximate to said openside, said housing closure having a pair of spaced-apart integral legsextending therefrom, said legs being in straddling relationship to saidbight and having their free ends against said wires thereby to retainsaid wires in said slots.